74 PRACTICAL PHYSIOLOGY. [iX. 



reaction owing to the presence of (NH4)2S04 a great excess of soda 

 has to be added. 



(/'.) Keutralise part of the filtrates of B and C. They give no 

 precipitate, nor do they give the reactions for peptones. In B the 

 ferment pepsin was destroyed by boiling, while in C the ferment 

 cannot act in an alkaline medium. 



{g.) If to the remainder of C acid be added, and it be placed 

 again at 40° C, digestion takes place, so that neutralisation has not 

 destroyed the activity of the ferment. 



Instead of fibrin white of egg may be used. 



The methods used by Kiihne to isolate the varieties of albumose 

 are purposely omitted here (p. 78). 



Products of Gastric Digestion. 



To 50 grams well-washed and boiled fibrin + 250 cc 0.2 per cent. 

 HCl. Digest for twenty-four hours at 40° C. Neutralise with sodium 

 carbonate. 



Precipitate =Acid- Filtrate : Albumose + Peptone, 



albumin. ' Saturate with (NH4)2S04. 



Precipitate = A Ibumoses. Filtrate : Peptone + (N"H4)2S04. 



Boil with Barium Carbonate. Boil with Barium Carbonate. 



I 



Residue of Filtra,te^ A lbu7nose- Residue of Filtrate = Pe//<(m<j- 



Barium Sulphate, solution wliich can Barium Sulphate, solution containing 



be precipitated by Baryta. Precipitate 



alcohol. peptone by alcohol. 



5. Tests for Albumose (Lesson I. 10). — It is precipitated by 

 the following substances : Nitric acid ; acetic acid and NaCl ; acetic 

 acid and ferrocyanide of potassium. The precipitates are soluble 

 on heating and reappear on cooling. In all these respects it 

 diff'ers from peptone. Like peptone, however, it gives the biuret 

 reaction, and is not coagulated by heat. 



6. Test for Peptones (Lesson I. 10, VI.). 



The following table from Halliburton shows at a glance the chief 



